In a conventional disc changer, a disc holding means is configured to house a plurality of subtrays in a stocker having a plurality of shelves, and a vertical driving means for selecting the position of an arbitrary disc is configured to drive all of the stocker, the plurality of subtrays, and the plurality of discs in the vertical direction.
In the conventional disc changer, however, while the vertical driving means for driving a disc holding means to select an arbitrary disc position is effecting driving, the large weight of the stocker having the plurality of shelves and the disc holding means for driving all of the plurality of subtrays and discs may cause a vertical driving motor to consume a large amount of energy or cause falling of finished discs or inappropriate vibration. In addition, the large number of parts increases costs.
Then, a recently contemplated disc changer comprises a disc holding means 204 for detachably supporting a plurality of spacers 203 on a pair of spindles 201 and 202 using a holding claw 200, a vertical driving means 205 for driving the spacers 203 in the vertical direction to select arbitrary positions of a plurality of discs 223 and 224 held by the plurality of spacers 203, a spindle driving means 206 for driving the holding claw 200 to engage and disengage the plurality of spacers 203 with and from the upper spindle 201, a horizontal transfer means 207 for transferring discs 223 and 224 to a recording/playing position E from arbitrary spacers 203 held by the holding claw 200, while supporting the discs on subtrays 225, and a disc clamp means 208 for clamping the discs 223 and 224 at the recording/playing position E, for example, as shown in FIGS. 43 to 45.
The disc changer of this configuration can drive in the vertical direction the plurality of spacers 203 and plurality of discs 223 and 224 installed on both spindles 201 and 202 to shift the arbitrary disc 223 or 224 from the spindle 201 or 202 to the recording/playing position E, then to an unloading position G, and back to a housing position F on the spindle 201 or 202, and can select the arbitrary disc 223 or 224 for recording/playing. Thereby, this configuration eliminates the needs for a stocker having a plurality of shelves or a plurality of subtrays to reduce the weight and costs, and provides a disc changer having excellent housing and operating capabilities.
In this disc changer, however, separate elevating cams 209 and 210, connecting mechanisms 211 and 212 and lock means 213 and 214 were used to execute driving including the elevation and lowering of the disc holding means 204 using the spindles and the elevation and lowering of the disc clamp means 208 to clamp the discs 223 and 224 at the recording/playing position E. Consequently, the apparatus was complicated and loads of the elevating cams 209 and 210 enormously varied when the spindles 202 of the disc holding means 204 and the disc clamp means 208 were simultaneously driven to elevate and lower, respectively, resulting in problems such as an unstable operation during the elevating driving caused by an insufficient driving force and a high operation noise during the lowering driving.
Furthermore, since a horizontal transfer means 207 for transferring a tray 215 depended on driving based on the engagement between a single driving gear 216 and racks 217 and 218 provided for each part, the driving was carried out at a single reduction gear ratio to preclude the reduction gear ratio from being adjusted to account for operation loads, thereby preventing requirements for both the operation time and load margin from being met.
Furthermore, due to the independency between a vertical driving system for driving in the vertical direction the spacers 203 holding the discs 223 and 224 and a horizontal driving system for driving the elevation and lowering of the spindle and transferring the tray 215, separate driving sources had to be provided for these systems, and intermediate gears were also required. As a result, the number of required parts was increased to increase the size and costs of the apparatus.
Moreover, in order to compactify the changer, an attempt was made to reduce the distance between the recording/playing position E and the disc holding position F so that the disc 224 at the recording/playing position E appeared to partly overlap the disc 224 at the disc holding section as seen from above. Due to vibration, however, the disc housed adjacent to the disc 224 under recording/playing at the disc holding section contacted the disc 224 under recording/playing to cause an accidental track shift or to damage the disc.
Furthermore, in order to integrate the independent driving sources into a single common source, an attempt was made to allow part of the gear train to be shared by both the driving system for the vertical driving of the spacers 203 and the horizontal driving system and to use a gear that slided in the axial direction to select the engaged driving system, as a means for switching the driving. When, however, the gear sliding in the axial direction started to engage with the gear of the driving system upon driving switching, it was blocked and failed to effect switching, causing the apparatus to stop with an abnormal noise.
Moreover, the disc clamp means 208 was elevated from and lowered to the recording/playing position E by engaging a lateral pair of pins 221 on a disc playing means 220 with cam grooves 219 formed in right and left elevating cams 210. In this case, during elevation and lowering, the disc playing means 220 might be rotationally moved via the pins 221. If two left pins and one right pin were used instead of the lateral pair of pins 221 to solve this problem, the stroke of the right and left elevating cams 210 increased, resulting in another new problem that size of the apparatus increased.
Furthermore, when the tray 215 was opened to change the disc, a disc of a small diameter 223 such as 8 cm might accidentally fall into the apparatus due to a large opening 222 in the front surface of the apparatus.